This invention relates to new and useful apparatus for sensing meteorological conditions in the atmosphere and more particularly relates to a radiosonde capable of measuring conditions, such as, temperature, humidity, wind velocity, direction and pressure in a reliable and highly effective manner.
Various types of radiosondes have been devised for measuring conditions in the upper atmosphere. In many cases where it is desired to measure dry and wet bulb temperature conditions, it is customary to employ what may be termed a disposable sonde which can be suspended from a balloon so as to ascend into the upper atmosphere; and when the balloon bursts the sonde will become freefalling and with the assistance of a parachute drop back to earth. Even in those instances where basic measurements of temperature are required, one particular problem has been that of providing the necessary aspiration or airflow over the temperature sensors, since the natural flow of air resulting from ascension is insufficient for accurate psychometric relative humidity measurements. For this reason, means such as mechanical or electrical fans are employed to establish the necessary air movement over the temperature sensor. Reference is made for example to the article entitled "A Small Tethered Balloon Sounding System" which appeared in the September 1975 issue of the American Meteorological Society, pages 964-969 describing the problems and approaches which have been taken in the past to wet and dry bulb temperature measurements.
It has also been proposed to employ some vane members to cause gyration of the sonde in order to increase its stability and here reference is made to U.S. Pat. Nos. 2,717,309 to Campbell and 3,260,940 to Deisinger. Nevertheless it is desirable to provide for a radiosonde which is capable both of providing wet and dry bulb temperature measurement as a result of the natural airflow created by spinning the sonde itself and at the same time to so configure the apparatus as to provide and establish a controlled rate of descent and proper aerodynamic stability of the sonde without the aid of a parachute. In this way the weight and size of the sonde can be materially reduced with more favorable aerodynamic stability than has been previously realized. Moreover it is desirable to provide a sonde of the type described which will readily adapt itself for use in combination with a tethered balloon system in which the sonde can be suspended from the tethered balloon and permit it to spin freely about its main or longitudinal axis. In this relation, the sonde may be supported on a wind-vane supporting frame also free to pivot about the axis of the sonde so as to facilitate wind velocity measurements; or may be used with counter-rotating vanes when suspended from a free balloon to provide a measure of vertical air motion.